About

Paola Cappellaro received her undergraduate and master degrees from Italy (Politecnico di Milano) and France (Ecole Centrale Paris), and earned her Ph.D. in 2006 from MIT. She then joined Harvard University as a postdoctoral associate in the Institute for Theoretical Atomic, Molecular and Optical Physics (ITAMP), before returning to MIT as a faculty member in 2009. She is the Ford Professor of Engineering and a Professor of Physics at MIT, specializing in spin-based quantum information processing and precision measurements in the solid state. Her research aims to design and control quantum devices for quantum simulations, computation, and quantum sensing. She combines theoretical insights into the dynamics of spin qubit systems with experimental control expertise to address challenges in developing robust and scalable quantum devices. Notably, she pioneered quantum magnetic sensing using electronic spin defects in diamond, contributing significantly to the field of quantum information science and atomic physics.

Research topics

• Physics
• Quantum mechanics
• Computer Science
• Materials science
• Engineering
• Nanotechnology
• Theoretical physics
• Genetics
• Statistical physics
• Electronic engineering
• Condensed matter physics
• Biology
• Optoelectronics

Selected publications

• Enhancing Spin Coherence of Optically-Addressed Molecular Qubit by Nuclear Spin Hyperpolarization

  arXiv (Cornell University) · 2026-03-29

  preprintOpen access

  Optically addressable molecular triplet spins provide a chemically tunable platform for quantum application, but their coherence is often limited by interactions with surrounding spin baths. Here we demonstrate controlled suppression of nuclear-bath-induced decoherence in photoexcited triplet spins of pentacene co-crystallized in high-purity naphthalene single crystals. By hyperpolarizing the proton spin bath through triplet dynamic nuclear polarization (triplet-DNP), magnetic noise generated by the nuclear spins is suppressed, leading to an extension of the electron spin transverse coherence time. Experimentally, we observe a 25\% enhancement of the spin-echo decay time with $60\%$ polarization of the proton spin bath. The measured scaling of the spin-echo decay time ($T_2$) with nuclear polarization quantitatively follows the predicted dependence derived from the polarization-controlled nuclear second moment. Both the enhancement and the absolute value of the coherence time are quantitatively reproduced by cluster correlation expansion (CCE) simulations. These results establish nuclear spin hyperpolarization as a general and actively tunable approach to engineering coherence in molecular qubits. This work provides a broadly applicable design framework for high-coherence molecular and solid-state spin systems.

  PublisherDOI

• Enhancing Spin Coherence of Optically-Addressed Molecular Qubit by Nuclear Spin Hyperpolarization

  arXiv (Cornell University) · 2026-03-29

  articleOpen access

  Optically addressable molecular triplet spins provide a chemically tunable platform for quantum application, but their coherence is often limited by interactions with surrounding spin baths. Here we demonstrate controlled suppression of nuclear-bath-induced decoherence in photoexcited triplet spins of pentacene co-crystallized in high-purity naphthalene single crystals. By hyperpolarizing the proton spin bath through triplet dynamic nuclear polarization (triplet-DNP), magnetic noise generated by the nuclear spins is suppressed, leading to an extension of the electron spin transverse coherence time. Experimentally, we observe a 25\% enhancement of the spin-echo decay time with $60\%$ polarization of the proton spin bath. The measured scaling of the spin-echo decay time ($T_2$) with nuclear polarization quantitatively follows the predicted dependence derived from the polarization-controlled nuclear second moment. Both the enhancement and the absolute value of the coherence time are quantitatively reproduced by cluster correlation expansion (CCE) simulations. These results establish nuclear spin hyperpolarization as a general and actively tunable approach to engineering coherence in molecular qubits. This work provides a broadly applicable design framework for high-coherence molecular and solid-state spin systems.

  PublisherOA PDF

• Numerically Optimizing Shortcuts to Adiabaticity: A Hybrid Control Strategy

  arXiv (Cornell University) · 2026-04-01

  preprintOpen access

  Achieving fast, excitation-free quantum control is a vital challenge in modern quantum technologies. In many cases, shortcuts to adiabaticity enable fast adiabatic-like protocols, yet determining control parameters that satisfy practical constraints is often challenging in complex systems. Here, we combine an analytical shortcut to adiabaticity approach with several numerical optimization methods to boost the performance of the protocol. As a proof-of-principle for this hybrid approach, we study a particularly intricate control problem, the separation of two trapped ions. We show that this analytical-numerical approach, along with the physical insight gained through the variety of suboptimal solutions, leads to the exploration of new solutions in a complex landscape that yield improvements of up to 3 orders of magnitude. Moreover, this improvement comes with no additional cost from an experimental point of view.

  PublisherDOI

• Numerically Optimizing Shortcuts to Adiabaticity: A Hybrid Control Strategy

  ArXiv.org · 2026-04-01

  articleOpen access

  Achieving fast, excitation-free quantum control is a vital challenge in modern quantum technologies. In many cases, shortcuts to adiabaticity enable fast adiabatic-like protocols, yet determining control parameters that satisfy practical constraints is often challenging in complex systems. Here, we combine an analytical shortcut to adiabaticity approach with several numerical optimization methods to boost the performance of the protocol. As a proof-of-principle for this hybrid approach, we study a particularly intricate control problem, the separation of two trapped ions. We show that this analytical-numerical approach, along with the physical insight gained through the variety of suboptimal solutions, leads to the exploration of new solutions in a complex landscape that yield improvements of up to 3 orders of magnitude. Moreover, this improvement comes with no additional cost from an experimental point of view.

  PublisherOA PDF

• Electron spin dynamics guide cell motility

  ArXiv.org · 2025-03-04

  preprintOpen access

  Diverse organisms exploit the geomagnetic field (GMF) for migration. Migrating birds employ an intrinsically quantum mechanical mechanism for detecting the geomagnetic field: absorption of a blue photon generates a radical pair whose two electrons precess at different rates in the magnetic field, thereby sensitizing cells to the direction of the GMF. In this work, using an in vitro injury model, we discovered a quantum-based mechanism of cellular migration. Specifically, we show that migrating cells detect the GMF via an optically activated, electron spin-based mechanism. Cell injury provokes acute emission of blue photons, and these photons sensitize muscle progenitor cells to the magnetic field. We show that the magnetosensitivity of muscle progenitor cells is (a) activated by blue light, but not by green or red light, and (b) disrupted by the application of an oscillatory field at the frequency corresponding to the energy of the electron-spin/magnetic field interaction. A comprehensive analysis of protein expression reveals that the ability of blue photons to promote cell motility is mediated by activation of calmodulin calcium sensors. Collectively, these data suggest that cells possess a light-dependent magnetic compass driven by electron spin dynamics.

  PublisherOA PDF

• Energy exchange statistics and fluctuation theorem for nonthermal asymptotic states

  Physical review. E · 2025-01-21 · 1 citations

  article

  Energy exchange statistics between two bodies at different thermal equilibria obey the Jarzynski-Wójcik fluctuation theorem. The corresponding energy scale factor is the difference of the inverse temperatures associated to the bodies at equilibrium. In this work, we consider a dissipative quantum dynamics leading the quantum system towards a possibly nonthermal, asymptotic state. To generalize the Jarzynski-Wójcik theorem to nonthermal states, we identify a sufficient condition I for the existence of an energy scale factor η^{*} that is unique, finite, and time independent, such that the characteristic function of the energy exchange distribution becomes identically equal to 1 for any time. This η^{*} plays the role of the difference of inverse temperatures. We discuss the physical interpretation of the condition I, showing that it amounts to an almost complete memory loss of the initial state. The robustness of our results against quantifiable deviations from the validity of I is evaluated by experimental studies on a single nitrogen-vacancy center subjected to a sequence of laser pulses and dissipation.

  PublisherDOI

• List of contributors

  Elsevier eBooks · 2025-01-01

  book-chapter
  PublisherDOI

• Diamond color centers for enhanced quantum sensing

  Elsevier eBooks · 2025-01-01

  book-chapterSenior author
  PublisherDOI

• Disorder-Induced Anomalous Diffusion in a 3D Spin Network

  arXiv (Cornell University) · 2025-10-10

  preprintOpen accessSenior author

  Emergent hydrodynamics (EHD) bridges short-time unitarity with late-time thermodynamics, universal transport phenomena characterize the manner and speed of transport and thermalization. Typical non-integrable systems with few conserved local quantities are expected to be diffusive. In contrast, strongly disordered systems which admit phases such as many-body localization, are predicted to inhibit thermalization and thus slow dynamical transport. Disordered systems represent a uniquely poised platform to probe the quantum-to-classical transition and the emergence of irreversible thermodynamics from the underlying unitary structure. Here, we study a strongly disordered nuclear spin ensemble, using local measurements enabled by the disordered-state technique. We observe an apparent phase transition into a sub-diffusive regime, which we model as a random walk on the emergent fractal structure of a percolating network in the dipolar spin ensemble. Our novel theoretical model provides a framework for characterizing the emergence of thermalization in closed quantum systems, even in the presence of strong disorder.

  PublisherOA PDFDOI

• Erratum: Solid-state <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Th</mml:mi><mml:mprescripts/><mml:none/><mml:mn>229</mml:mn></mml:mmultiscripts></mml:math> nuclear laser with two-photon pumping [Phys. Rev. A <b>108</b>, L021502 (2023)]

  Physical review. A/Physical review, A · 2025-09-29

  article
  PublisherDOI

Recent grants

• Spin Bath of a Central Spin System in Diamond: Polarization and Coherent Control

  NSF · $300k · 2010–2014

• Quantum Simulation of Out-of-Equilibrium Spin Models

  NSF · $379k · 2019–2023

• Spectroscopy with Quantum Sensors at the Nanoscale

  NSF · $360k · 2017–2021

• Spin Polarization and Transport at the Nanoscale

  NSF · $420k · 2014–2018

Frequent coauthors

• Ashok Ajoy

  Lawrence Berkeley National Laboratory

  48 shared

• Mikhail D. Lukin

  Harvard University

  42 shared

• Changhao Li

  39 shared

• Ronald L. Walsworth

  University of Maryland, College Park

  37 shared

• Nicole Fabbri

  European Theoretical Spectroscopy Facility

  35 shared

• J. S. Hodges

  35 shared

• Chandrasekhar Ramanathan

  32 shared

• Yi-Xiang Liu

  Southern University of Science and Technology

  27 shared

Awards & honors

• 2023 // American Physical Society Fellow
• 2020 // Committed to Caring Award
• 2014 // Merkator Fellowship
• 2013 // Esther and Harold E. Edgerton Career Development Pro…
• 2012 // Air Force Office of Scientific Research (AFOSR) Youn…